Li, who is married with a young son, had worked for the technological supervision bureau in the city in Henan province.

The 35-year-old dug the dungeon in the basement of a residential compound he bought in 2009, the court heard, according to Xinhua.

He then used the underground room to hold women he tricked into coming to the property. Police investigations indicated the six were held captive for between two and 21 months.

Li repeatedly raped the women, forced them to appear in pornographic web shows from March to April 2011 and made them have sex with customers for a brief period last year, the court heard.

Three of the women were also found guilty of murder over the killings of two of their fellow captives, Xinhua reported.

However, the court was lenient in its judgment of the women because of the circumstances in which they were held, finding they acted under instruction, and in one case coercion, from Li. One of the women was sentenced to three years in prison and the other two were placed on probation.

The women had worked at karaoke bars, hair salons and a massage shop before they were kidnapped by Li, police are cited as saying.

Li's intention was to make money from selling the women's sexual services and uploading obscene videos to the Internet, the court heard.

His actions were brought to light only after one of the women escaped in September last year and alerted police. Li was then arrested.

Soon afterward, the head of the public security bureau in Luoyang apologized for the police failure to uncover the dungeon sooner and said they were taking new steps to clamp down on vice, according to a Xinhua report at the time.